BEHAVIORS OF HYDROGEN AND OXYGEN ON CLANED SILICON SURFACES

Silicon surfaces of CZ-grown wafer have been investigated by time-of-flight type electron-stimulated desorption spectroscopy (TOF-ESD). Though such surfaces had been believed to be clean enough after heating and flashing in UHV, considerable amounts of hydrogen and oxygen ions were detected by TOF-ESD on these surfaces. The yield of ESD oxygen ions decreased during cooling of the specimen to liquid nitrogen temperature after heating. The proton yield increased normally during cooling after flashing because of hydrogen diffusion from the bulk. Total cross sections of proton and oxygen ions for slow electron irradiation are estimated to be on the order of 10(-19) cm2.